Manufacture of stay bolts



April 30, 1929.

H. M. CURRY. JR., ET AL MANUFACTURE OF STAY BOLTS Filed Nov. 15, 1926 legzz."

Fig. 10.

jnekenfiars:

fi E/veY M 606 die. id LE0 f'7/V564M Patented Apr. 39, 1929.

uni-reo- STAT S PATENT OFFICE.

HENRY M. CURRY, m, on rrtr'rsnunen, Ann LEO FINEGAN, or 'ZELIENOPLE, PENN- V SYLVANIA, Assienoas "no PREIvEiiEE-t srnYnoL'rcoMrANY, or PITTSBURGH,

PENNSYLVANIA, A CQRPUEATTGN OF PENDlSYLVANIA.

Maivure'crunn on srAY norms.

' Application filed lqovember 15,1926. Serial No. 148,357.

This invention relates to the manufacture of staybolts, and more particularly to hollow st-aybolts having an enlarged solidhead formed integral with the hollow body of the bolt.'

The manufacture of bolts of this class has heretoforeheen' a matter of considerable ditliculty. The formation of the central bore in such bolts after they are formed by boring or drilling is diflicult and expensive, due to thesmall diameter and length of the bore which requires a small diameter drill of considerable length, necessitating slow drilling in order to prevent excessive break age of the drills.

The present invention overcomes the, above difliculties and provides a simple, practical and comparatively inexpensive method by which such bolts may lie-manufactured.

In the drawings-- Figure 1 is a plan of the blank from which the stayholt is formed.

Figure 2 is an end elevation thereof.

Figure 3 is a sectional View through the blank after the bore has been formed.

Figure l is. an end elevation thereof.

Figure 5 is a sectional View through the blank after it has been reduced.

Figure 6 is an end elevation thereof.

Figure 7 is a sectional view through the blank after it has been upset to form the head. Figure 8 is an end elevation thereof. Figure 9 is a sectional view through the blank after the bore has been reamed out to true up its cross'sectionr Figure 10 is a sectional view through the finished bolt after the threading operation.

In carrying out the present invention, we first provide a solid. cylindrical blank 2 of materially greater diameter and lesser length than the finished bolt, as indicated in Figure 1. The blank 2 is then drilled or bored along its longitudinal axis to provide the hollow center or bore 8, as shown in Figures 3'and 4-, which terminates materially short of the one end of'the blank leaving a solid end 4 to provide stock from which the head of the bolt may be formed. The bore 3, which is formed in the blank, is materially shorter and of materially greaterdiameter than the bore of the finished bolt. Therefore, it may be formed by drill of materially greater diameter. Due "tOl/ll'o greater diameter of the drill, compared with that which would be usable to drill the finished bore, the drill hasgrcater strength and maybe forced at greater speedintocthe blank, and this coupled with the, relatively shorter length of.

operation to form the round head 6' and to slightly enlarge the shank portion 7 of the blank adjacent the head to form a tapered area 8, as shown in Figures 7, 9 and 10.

The upsetting operation will cause the metal to flow inwardly adjacent the head end of the bore 5 forming a restriction 9. The bore 5 is then preferably reamed out by passing a drill or reamer of the proper size therethrough, to remove the restriction 9 and true up the bore 5. This operation may be performed with considerable speed due to the fact that the bore is preformed and the only substantial distortion will be the restriction 9.

If found desirable or necessary the outer surface of theblank may be machined either before or immediately after the reaming operation. I

The headed and reamed blank is then threaded adjacent its unheaded end, as at 10, to form a finished bolt consisting of the head 6,'shank 7 havingthreads 10 at its u'nheaded end, and the bore 5, as shown in Figure 10.

sequence of steps for carrying out our method, it will be understood that we do not Wish to be limited thereto, since various modifications may be practiced without departing from the scope of our invention as defined in the appended claim.

We claim:

The method of making hollow staybolts, which includes providing a cylindrical blank of greater diameter and less length than the finished bolt, boring out the center of said blank for part of its length to form a bore of materially greater diameter than the bore in the finished bolt, reducing said blank over its entire length without providing an internal support for said bored out portion so as to simultaneously elongate and reduce the diameter of said blank and said hollow center, upsetting the solid end of said blank to form a head portion extending beyond the closed end of said bore, permitting the metal of said blank to flow both outwardly and 20 inwardly over a short length of the bored out portion of said blank adjoining the solid end during said upsetting operation to form a tapered portion of shank adjoining said head and to prevent the closing off the bore of said shank, said upsetting operation resulting in reducing the diameter of but not closing the bore in said blank adjacent its closed end and in shortening said blank to the length of the finished bolt, reaming out said bore adjacent said head end of said blank to true up its diameter, and finally threading the unheaded end of said blank to finish the bolt.

In testimony whereof, I have hereunto set my hand.

HENRY M. CURRY, JR. In testimony whereof, I have hereunto set my hand.

LEO FINEGAN. 

